The invention relates generally to graphics processing and more particularly to a method and apparatus for multi-pass texture mapping in a video graphics system.
Computers are used in many applications, and in some of these applications, detailed graphical images are generated. The generation of such detailed images may include the use of texture maps. Texture maps are often molded and adapted to overlay or map to objects, or video graphics primitives, for display. One example of the use of a texture map is mapping a checkered pattern onto a spherical structure.
In some cases, multiple textures are used to further enhance the visual details associated with different objects included in the display. For example, the surface of the spherical structure may have a topography that is covered with bumps. The presence of the bumps on the surface of the spherical structure will affect the way in which the checkered pattern is visible to an observer. As such, both the checkered texture map and a texture map corresponding to the bump covered topology of the surface of the sphere may be used to perform the texturing of the spherical structure.
In prior art systems, multiple texturing blocks were used to map multiple textures to different objects or primitives. As such, when multiple textures were to be applied to different objects, multiple texturing blocks were required in the video graphics processing circuitry. The inclusion of such additional texturing blocks increases the complexity of such circuits and adds to their cost. As such, the inclusion of multiple texturing blocks for such reasons is undesirable.
Therefore, a need exists for a method and apparatus that permits objects to be textured using multiple textures without the need for multiple texturing blocks in the video graphics processing circuitry.